The field of this invention is heat warning safety devices, and more particularly, such devices for warning individuals that a surface is dangerously hot.
With respect to stoves and related appliances, various kinds of stovesxe2x80x94electric, gas, smooth cooktop stoves which use glass or metal topsxe2x80x94and toaster ovens are well known to be used for heating food. In addition, xe2x80x9cmobile stove-type appliancesxe2x80x9d such as hot plates and warming trays are well known to be used for heating food. Each of these kinds of stoves and xe2x80x9cmobile stove-type appliancesxe2x80x9d present a safety problem since the heating elements of the stove are hot during the cooking process and remain hot well afterwards. During the cooking process, the safety problem caused by touching the heating element is mitigated somewhat by visual inspection of the stove. With a gas, electric or smooth top stove, for example, the presence of a pot or other utensil on top of the stove might alert someone to the fact that the stove appears to be in use for cooking and therefore too hot to touch. Even the presence of a pot or other utensil is not a reliable clue, however, since people tend to leave tea kettles on their stove perpetually. When the cooking process has ended, however, it is generally impossible to detect that the heating elements of the stove remains hot and would burn the skin of anyone who touched them. There is no visual or other clue that the stove is hot.
To some degree, adults have developed an inherent caution when approaching stoves because of their experience and knowledge in dealing with such safety problems. This inherent caution, however, does not obviate the need for a device that warns the adult when touching the stove would be dangerous. Moreover, children, and particularly young children, usually have not developed such a watchfulness and there has long been a need for a device that can prevent burn accidents to children who may inadvertently touch a stove that is hot, especially when the stove remains hot well after the cooking process has ended.
Furthermore, the reduction in the size of modem kitchens has led the occupants of modern apartments to make use of the stove as an extension of the counter top adjacent the stove as a resting places for large items that have been carried into the kitchen area. An example of such items is heavy bags of groceries brought into the kitchen. There is an urge to set the bags down on the nearest flat surfaces, which may be the top of a stove adjacent a counter top. This is particularly true for those stoves that are smooth on top, such as smooth cooktops. In general, the top surfaces of modern kitchen stoves are increasingly flat, especially the top surfaces of smooth cooktops. These factors have only increased the danger to adults when the top surfaces of stoves are used as a resting place for packages, such as groceries brought into the kitchen.
Smooth cooktop stoves presently are also dangerous if touched on their top surface when they are still hot, even after use. These smooth cooktop stoves, or xe2x80x9csmoothtopsxe2x80x9d as they are sometimes called, utilize as the heating element separate areas on the top surface of the stove (at the same location that gas stove would have burners) which are made of glass. Under each area, usually circular, is a strong light source, such as a halogen lights. The light source projects the light upward to the surface area of the smoothtop""s heating elementxe2x80x94the glass area on the top surface of the stove. Since the glass area is coated on its bottom with a dark coating, when the light strikes it, the heat from the strong light is absorbed by the glass area and these glass surfaces form each heating element of the stove.
Another variation of the smooth cooktop is the use of a xe2x80x9cribbon heating elementxe2x80x9d where the smooth glass surface is heated by a coiled electric circuit called a xe2x80x9cribbon elementxe2x80x9d just underneath it instead of by a halogen light source. The heat is transmitted directly upward so that only the heat element itself gets hot and the rest of the cooktop surface remains cool. In some cases, the ribbon heating element also has another feature whereby the heating element is made of two concentric circles so that the option exists of two sizes of the heating element to match the two different sizes of the pans that need to be heated. This new technology does not solve the problem of warning adults and children that the heating element should not be touched when the cooking process has ended. If anything, it generates the additional hazard that someone can be lulled into touching the heating element after thinking the heating element is cool since the surface right adjacent to it is indeed cool.
Some of these problems have been addressed in Applicant""s U.S. Pat. No. 6,104,007 and in pending patent applications, through use of heat warning safety devices that includes a warning symbol that appears directly on the heating element of a stove and by using thermochromic compositions such as for inserts or overlays. Thermochromic materials include liquid crystal (whether cholesteric or chiral nematic) compositions that change color when passing through a given temperature range, and such compositions are now familiar to consumers from their frequent use in inexpensive items, like temperature indicating refrigerator magnets or stick-on aquarium thermometers.
Presently, in order to address the danger of touching a hot xe2x80x9csmoothtopxe2x80x9d stove, such stoves generally have several light indicators, each one corresponding to each heating element, all located in small one rectangular area on the surface of the cooktop. The light indicators remain lit for a certain length of time after the stove""s heating element is turned off in order to deter someone from touching the heating element when it is still hot, although xe2x80x9coffxe2x80x9d. The light indicators themselves consist of a xe2x80x9cdotxe2x80x9d or red LED or other indicator, each dot corresponding to a different heating element. Unfortunately, this attempt to address the danger of touching a hot stove of the smooth cooktop variety is insufficient as a warning system (putting aside the fact that the light indicators as an indicator of residual heat after the heating element is turned off are presently designed only for the smooth cooktop variety stoves to begin with and not for gas and electric coil stoves).
A quick glance at the group of light indicators would not be sufficient to warn the average adult, no less children or the elderly, that a particular heating element is too hot. This is because the group of light indicators do not immediately tell someone which heating elements correspond to which light indicators. At a minimum, several seconds of concentration are needed in order to determine from the light indicators that are xe2x80x9conxe2x80x9d, which heating elements are too hot to touch. Many adults, and certainly most children, cannot afford those seconds of deduction since their desire to touch the stove is immediate. In addition, an adult carrying groceries into the kitchen and looking for a counter top to place them on or a child running into and playing in the kitchen are even less likely than the average adult or child to take the time to engage in a several second thinking process. Accordingly, the child or the adult will be inadequately warned about the danger of being burned. With this in mind, it is no surprise that a 1997 industrial design exhibit at the Cooper Hewitt (Smithsonian) in New York demonstrated that over 69% of adults can not match the control knob with its corresponding burner (i.e. heating element) on a stove.
Furthermore, the prior art heat indicators can be up to three feet away from the heating element to which they correspond. That distance is too far away for a dangerously hot surface. Surely one would not position a warning for an open air shaft three feet away.
Moreover, the use of a single red LED dot to communicate a warning of heat, while it may have been noticeable and effective in the kitchen of the past, is completely ineffective today. In today""s kitchen environment, the meaning of a dot of a red LED is dramatically diluted by the presence of a multitude of dots of red LED""s all over the place in the modem sophisticated kitchen. For example, many appliances in the kitchen such as coffee pots, cell phones, corded phones, answering machines, computers, televisions, rechargeable flashlights, personal digital assistant devices, dustbusters, alarm keypads and motion sensors all have red lights or red LED""s which dilute the meaning of a single red LED as an indicator of heat on a near by heating element.
There is also confusion of message from the prior art light indicators. In the electric stove the light goes off when the electric coil is turned off and no residual heat indicator exists. Light xe2x80x9coffxe2x80x9d means there could still be a danger of heat. In the smooth cooktop the light indicator does stay on when the heating element residually remains hot after being turned off. In this context light xe2x80x9coffxe2x80x9d means no dangerously hot surface. Thus the red light indicator means two different things depending on the context and this confuses the consumer and dilutes the effectiveness of the indicator lights as warnings.
The above problems with existing heat indicators are even more pronounced when considered in the context of today""s modern kitchen. The traditional kitchen in the past has been the domain of a stay at home mother. The kitchen contained one corded telephone and a cooktop stove would be plainly obvious and salient in such a kitchen. Today""s kitchen is much more distracting. In today""s kitchen, it is more common, at least in many households, for everyone to cook. Furthermore, the kitchen itself in many cases functions also as an entertainment room, a living room or a family room. The kitchen and its inhabitants feature cordless telephones, computers announcing xe2x80x9cyou have mailxe2x80x9d, cell phones, pagers and people milling about xe2x80x9cmultitaskingxe2x80x9d, talking, drinking, socializing and not just cooking. Guests may be unfamiliar with cooking areas. Smoothtop stoves are not so distinctive in this environment since they have been re-designed to blend into the kitchen design. Smoothtops are also not immediately recognizable as smoothtops because the new designs are odd in shape. Also, where previously versions had a vent hood that stuck out, such vent hoods are now often built into the cabinet and remain unseen, thus eliminating the visual cue telling you it is a cooking area. Furthermore, stoves appear in islands in the middle of the kitchen separate from any oven rather than against the wall and adjacent the oven. Hence, a potentially hot surface can be approached from four different directions in a distracting environment when the danger may be hard to recognize, it is not hard to see that the prior art indicators, such as shown in FIG. 1, which appear on only one side of a cooktop stove, are practically useless in today""s kitchen, even putting aside the fact that they require precious seconds of deduction to figure out which dangerously hot heating element it is supposed to correspond to the lit indicator warning light.
In addition, some people may not have grown up with smooth cooktops and may not recognize it. The elderly, children, visually impaired individuals would all have trouble using prior art heat warning indicators on a smoothtop to warn against the residual heat of a heating element on a smoothtop stove, or for that matter other stoves or hot surfaces.
Heat alert safety devices based on thermochromic compositions situated in the center of each heating element and containing a predetermined symbol which changes color at a specified temperature has been discussed in Applicant""s previous patents and patent applications, including U.S. patent application Ser. No. 09/788,594 filed Feb. 21, 2001 and U.S. patent application Ser. No. 10/429,111 filed May 2, 2003 and the aforementioned U.S. Pat. No. 6,104,007 to Lerner These devices offer many important advantages. One potential drawback, however, is that devices based on thermochromic compositions are limited to heat environments in which the thermochromic composition is reliable at color changing and is stable. Furthermore, a thermochromic composition does not instantly change color but changes color somewhat gradually. Thermochromic compositions are harder to see in the dark or poorly lit room.
Although LED""s may contain certain advantages over thermochromic composition when used in heat warning devices, to the extent that the hot surface is the hot surface of a smooth cooktop stove or of a gas stove, any heat warning device that requires electricity near the heating element to activate the warning symbol can be inappropriate. Since gas is combustible, it is undesirable to have an electric current near it. Moreover, with respect to an electric stove having a serpentine electric coil as the heating element, running a new set of electric wires to feed a set of LED""s functioning as the warning symbol runs the risk of electromagnetic interference between the different currents. Furthermore, with respect to smooth cooktop stoves, the heating element is formed by having a smooth area of glass or metal on the surface of the stove subjected to a heat source directly underneath that smooth area, for example a halogen lamp. Insulated electric wires running near the halogen lamp or other source of heat could be dangerous since smoothtops get as hot as 800 degrees Fahrenheit.
Consequently, there is a compelling need for a heat warning device that offers a heat warning symbol in an effective manner and in a manner that overcomes the disadvantages of the prior art. It is further desirable to have such a device with a heat warning symbol that does not require running an electric current near the heat warning symbol. Since the heat warning symbol itself necessarily has to be near a strong source of heat and in certain cases a combustible gas or an electric current, it is preferable to have a device that does not require running any electric current near the heat warning symbol. The present invention offers the above compelling advantages and many more advantages.
Preliminarily, moreover, it is noted that the present invention is applicable not just to stoves and related appliances, but to any other surface that one may need to be warned that it is hot, as long as it has access to a light source that can be activated under predetermined conditions. For example, there are numerous devices whose surfaces become hot and remain hot even after the device has been shut off either electrically or otherwise. For example, a radiator cap becomes hot and remains hot for a period when the vehicle and radiator are shut off. Also, any kind of piping that is a conduit for hot liquids is an example of a surface that one may need to be warned that it is hot. Other devices having hot surfaces include hot surfaces on fireplace doors, flat irons, chafing dishes, coffee urns, heating pipes, home radiators, glue guns, oven doors, portable heaters of the electric, oil and ceramic disc type, kerosene lamps, kerosene heaters, barbecue grills of the electric, gas or charcoal type, electric woks, electric skillets, deep fryers for home or commercial use, heat lamps in self service cafeterias and salad bars, saunas including the metal box that generates and/or controls the heat, rotisseries, indoor grills whether gas or electric, tea kettles, wood burning stoves, hot electric rollers, hot wax holders used for beauty treatments, bonnet type hair dryers, synthetic braid trimmers, curling irons, portable generators, steam cleaners especially such as in dry cleaning facilities, hot water pipes that are exposed, hot water heaters, furnaces, warming trays, light fixtures such as halogen lamps, popcorn makers (especially commercial ones), toasters, home and commercial cappucino and espresso makers, autoclaves used to sterilize instruments in a medical setting, movie projectors, industrial steam machines and pressers, the metal surfaces in the cooking areas on an airplane, heat producing generators and many other such hot surfaces. These and other hot surfaces are exposed to children, maintenance works and ordinary adult users.
A heat alert safety device for warning individuals that a surface is hot is provided wherein the device makes use of fiber optic cables that run from an electric light source to a heat warning symbol. The device includes a plurality of fiber optic cables connected at a first end thereof to the light source, the plurality of fiber optic cables transmitting light from the light source from the first end to the second end of said fiber optic cables and shining light out of the second end of said fiber optic cables to a predetermined symbol adjacent the second end of the fiber optic cables. The symbol is readily visible when lit to an observer who can also readily see the surface. The heat warning symbol communicates that the surface of the stove, in particular, the heating element, is dangerously hot. A well known controller controls the electric light source so that whenever a specified surface temperature is reached, the symbol is lit and remains lit as long as said specified surface temperature is maintained.
It should be noted that the device of the present invention can be seen in the dark. This is significant since sometimes people cook or entertain in their kitchen in the dark. For example, when warming a bottle for an infant in the middle of the night, the parent may rely only on the nightlight of 15 Watts and use electric appliances in the dark kitchen.
The following important objects and advantages of the present invention are:
(1) to provide a heat warning device that is able to instantly be illuminated whenever a specified temperature is reached;
(2) to provide such a device that can be adjusted in brightness (and power) depending upon the type of people likely to need the warning of being dangerously hot;
(3) to provide such a device that is reliable and stable regardless of the temperature levels in its environment up to at least 1200 degrees Fahrenheit;
(4) to provide such a device that can be used to warn that a surface of a gas stove may be dangerously hot wherein the fiber optic cable can run through or run adjacent to the gas inlet lines;
(5) to provide a heat warning safety device using a fiber optic cable that is smaller and lighter than electric wires;
(6) to provide a heat warning safety device that is not combustible;
(7) to provide a heat warning safety device that can be better used with electrical appliances since the device is immune to electromagnetic interference;
(8) to provide a heat warning safety device that can be used on electric stoves without using electric wires;
(9) to provide a heat alert safety device that combines visual and auditory cues to maximize warning impact;
(10) to provide a heat warning safety device that allows a person to instantly recognize which hot surface is dangerously hot and needs to be avoided;
(11) to provide a heat alert safety device that alerts people that a surface is dangerously ot even when the heat source that caused the surface to be hot has been turned off;
(12) to provide a heat warning device that is easy to manufacture and can be easily integrated into the manufacturing of known stoves;
(13) to provide a heat warning device that includes a heat warning symbol that appears directly on the heating element of a gas stove, an electric stove or a smooth cooktop or other stove or appliance including but not limited to grills and steamers;
(14) to provide a heat warning safety device that is effective for children, adults, the elderly and visually impaired individuals; and
(15) to provide such a heat warning safety device that can be readily seen and be effective in the dark.